Process of tanning.



CARL OTTO NATUSCH, OF HAMBURG, GERMANY.

PROCESS OF TANNHNG.

SPECIFICATION forming part of Letters Patent No. 662,804, dated November27, 1900.

Application filed July 21, 1899. serial No. 724,710. No specimens.)

To all whom it may concern:

Be it known that I, CARL OTTO NATUSCH, a citizen of the Empire ofGermany, residing at Hamburg, Germany, have invented certain new anduseful Improvements in Processes of Tanning, of which the following is aspecification.

Almost all the processes of quick tanning hitherto known furnish leatherof inferior quality which is often made very heavy with chemicalsubstances, such as metallic salts or the like. My new process,which maybe easily and readily carried into effect without special apparatus, maybe advantageously substituted for the usual tanning process which causesgreat loss of time and much trouble, and it produces a clear and softleather of any kind and for any purposes equivalent to leather producedby slow-tanning processes. The process may be employed for producing anykind of thin or thick leather for manufacturing boots and shoes, belts,&c., and for all technical purposes. Thin hides for manufacturing, forinstance, uppers of shoes may be perfectly tanned in three to ten daysand thick cowhides in about twenty-one days.

Vegetable matter containing tan min-such as catechu, divi-divi,myrobalan, or the like is submitted todecoction till a liquor of atleast 4 (four degrees) Baume is obtained, which liquor will be employedat a temperature of 36 to 42 Celsius. The proportions in which thesesubstances are employed cannot be determined, as they are varied inaccordance with the quality thereof; but the resultant liquor must be ofa strength of at least 4 (four degrees) Baum. Said liquor at 36 to 42Celsius is poured into wooden Vessels, and the prepared hides are thenhung or laid therein, and the liquor is allowed to cool (to about 12 to18 Celsius) and afterward heated again to 42 Celsius by leading steam orpouring fresh hot liquor into the vessels. After restoring thetemperature and again cooling a solution in about two cubic meters ofwater of one kilogram potassium dichromate is added to each one thousandto fifteen hunby slow-tanning processes.

dred liters of the liquor, and the whole then left until a perfecttanning is obtained-that is, during three to twenty one days, asaforestated.

The alternate heating and cooling of the liquor enables one to producefine, soft, and smooth leather which could not be produced if the liquorwere maintained at a temperature of 42 Celsius, in which case hardbreakable leather is obtained. The length of the immersion is determinedapproximately, the complete tanning being ordinarily obtained in one tothree days, in accordance with the thickness of the hides.

Thin hides serving to produce leather for fine uppers of shoes or bootsare dipped with out further addition into the liquor which remains afterthe execution of the process above described, said liquor is heated twoor three times, and a complete tanning will be obtained in three to tendays. This is not covered by any claim.

By the above process a considerable saving of tannin containingmaterials,time, and work will be obtained, and a high-grade leatherproduced which is almost equal to that produced The foregoing processenables one to produce anynkind of light-colored, soft, and flexibleleather, as Well as hard rigid leather, for any purposes.

Having fully described my invention, what I claim, and desire to secureby Letters Patcut, is-- The process of quick tanning which consists inimmersing the hides in a decoction of tanning containing materials at atemperature of 36 to 42 Celsius, of about the strength specifi-ed;cooling the same; restoring the temperature and again cooling; adding asolution of potassium dichromate to the said liquor and allowing thehides to remain in the resulting solution till the hides are completelytanned, substantially as described.

CARL OTTO NATUSCH.

Witnesses:

E. H. L. MUMMENHOFF, GEO. LENDRE.

